Non-touch HMI numeric entry with function keys: set keypad style 2

What keypad style 2 does

A function key has no built-in meaning. Even on a plain PC keyboard, the twelve keys F1 to F12 do only what the running program assigns them. On an HMI the same rule applies: until the project gives the keys a job, the question of whether one press raises or lowers the setpoint has no number behind it.

Keypad style 2 is that job. The selector sits in the Numeric object's own entry setup: on the numeric entry setup screen, in the lower-left area, you choose which keypad the object uses. Style 2 makes the function keys the entry keys. When the operator opens the entry, the prompt takes its input from the physical keys, the way an on-screen keypad takes input from touches. On a touch panel you would draw or link that keypad yourself; linking a user-defined keypad to an HMI numeric entry object covers that route, and the numeric entry object style for a non-touch HMI keypad covers the object-side style settings behind the prompt. Keypad entry of setpoints is a standard pattern on compact panels; this walkthrough of setpoint entry on a compact keypad HMI shows the same idea on another small panel.

Nothing in the keypad-style selector defines a step amount. If the line needs buttons that add or subtract a fixed amount, that is a separate object, an increment or decrement button, with the result clamped in ladder logic so the value stays in range.

What you need

• The panel's configuration software and the project file.
• The Numeric object the operator uses for this setpoint, with its tag, allowed range and scaling written down before you change anything.
• The panel on a bench, or the machine in a safe state, for the transfer and the test.
• The programming or monitoring tool for the controller, so you can read the setpoint register directly.
• One permitted test value agreed for the line.

Set keypad style 2, step by step

1. Open the project in the panel's configuration software.
2. Select the Numeric object the operator uses to change this setpoint.
3. Open that object's numeric-entry setup screen.
4. In the keypad selector at the lower left of the screen, choose keypad style 2.
5. Confirm the object accepts operator entry and points at the setpoint tag. If the operator can see the value but cannot edit it, the object is set up as a display, and the entry settings on this screen are where that changes.
6. Save the project and transfer it to the panel with the software's normal transfer workflow.
7. Open the entry for the object on the panel and type a few digits with the function keys while the machine is still in its safe state. The prompt should take the keys as input.

Test the entry on a stopped process

A re-configured panel writes to a controller, and its first write lands on a real machine. Make the test with the machine in setup or manual mode and motion disabled, the same discipline as the operator panel PLC link setup that tests writes before motion is enabled. Enter the agreed test value on the panel, confirm the entry, then read the setpoint register in the controller's programming tool and compare the two numbers. What fires when the entry lands in controller memory is covered in moving an HMI numeric entry into PLC memory on Enter.

Set the allowed range in the controller as well, so a mistyped entry cannot command an unsafe value; clamping numeric entry limits in ladder logic shows the pattern. If the controller acts only after a handshake bit sets, confirm that flag too; numeric entry notification and handshake bits explained covers the flags.

Example: enter 185.0 °C and follow it to the register

Scenario: an oven setpoint is allowed 100 to 200 °C, and the project scales the Numeric object by 10, so the controller register holds tenths of a degree. The operator opens the entry on the non-touch panel, types 185.0 with the function keys, and confirms.

The register should hold 185.0 × 10 = 1850 counts. Open the register in the programming tool. A read-back of 1850 confirms the whole path: keys, object scaling, write. A read-back of 185 says the scaling is missing where you assumed it. Read as tenths, 185 counts are 18.5 °C, which sits 166.5 °C below the 185.0 °C the operator typed. The fix is the scaling setting, in the object or in the ladder, and it is not a new typing habit for the operators.

Where the decimal point is handled decides this mapping. If the controller holds the decimal handling in a tag, moving an HMI numeric entry decimal point from a PLC tag covers that side.

How to check it worked

• The entry opens from the object, and the prompt appears on the panel.
• The function keys type digits into the prompt, and the entry accepts the value.
• The controller register reads the counts you predicted from the object's scaling.
• The handshake bit, where the controller uses one, sets and clears as expected.
• An out-of-range entry is rejected or clamped by the controller.

If the keys do nothing, the style change usually sits on a different object than the one on screen, or the transferred project is not the one running. If the register is wrong by a factor of ten, scaling is the suspect. A display value and a register value that disagree are a stop condition: re-check the object and the scaling before the panel goes back on the wall, and do not paper over the gap with a step amount.

The decision

Recommendation: set keypad style 2 in every Numeric object a non-touch panel operator must edit, and prove each one with a single test entry read back from the controller register while the machine is in a safe state. Pick the route by hardware: on a touch panel, link a user-defined keypad to the object; on a panel with a function-key row, style 2 is the whole fix; on a panel with neither touch nor function keys, add the entry at the controller, the way a project that adds keypad entry to a PLC over its native protocol does it.

Where a signage display fits

A panel configured this way is the machine's HMI. A signage display is a different screen with a different job: if the cell also needs a standalone andon board or notice screen beside the machine, our shop-floor signage plays loaded files offline and leaves the controller writes to the HMI.

Questions